What does the term Holocaust refer to?
The genocide of Gypsies, Jehovah's Witnesses, homosexuals, and 6 million Jewish people. Jews refer to the Holocaust as "Shoah".
There are, however, two competing definitions. When used by professional historians it refers to the Nazi genocide of the Jews.
"The standard work by the distinguished Canadian historian Michael Marrus, The Holocaust in History, focused on, to use his own words, 'the Holocaust, the systematic mass murder of European Jewry by the Nazis'. Similarly, Sir Martin Gilbert, in his documentary compilation, The Holocaust: The Jewish Tragedy ( London, 1986), concurred in referring to 'the systematic attempt to destroy all European Jewry - an attempt now known as the Holocaust'. Another author, Ronnie S. Landau, put forward a similar definition in his book, The Nazi Holocaust: 'The Holocaust involved the deliberate, systematic murder of approximately 6 million Jews in Nazi-dominated Europe between 1941 and 1945."
Richard J. Evans, Telling Lies About Hitler: The Holocaust, History and the David Irving Trial, Verso, London and New York, 2002, pp. 113-4.
More popularly, especially in the US, it is extended to all people killed by the Nazis on the basis of their group membership.
Yet a third view is gaining ground - namely, the the Germans fought a 'war of annihilation' (mainly on the Eastern Front) and that this attempt to reduce the population of Eastern Europe by about 30 million was the core of the Holocaust, though it included some other groups.